engleski

Thermodynamic study of dihydrogen phosphate dimerisation and complexation with novel urea- and thiourea-based receptors

Complexation of dihydrogen phosphate by novel thiourea and urea receptors in acetonitrile and dimethyl sulfoxide was studied in detail by an integrated approach using several methods (ITC, ESI-MS, 1H NMR and UV spectroscopies). Thermodynamic investigation of H2PO4– dimerisation, a process which has been frequently recognised but rarely quantitatively described, was carried out as well. The corresponding equilibrium was taken into account in the anion binding studies enabling reliable determination of the complexation thermodynamic quantities. In both solvents the thiourea derivatives exhibited considerably higher binding affinities with respect to that comprising urea moiety. It was found that in acetonitrile 1:1 and 2:1 (anion:receptor) complexes were formed, whereas in dimethyl sulfoxide only the significantly less stable complexes of 1:1 stoichiometry were detected. The solvent effects on the thermodynamic parameters of dihydrogen phosphate dimerisation and complexation reactions were disscussed.

dihydrogen phosphate ; dimerisation ; anion binding ; receptors ; thermodynamics

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